reg4b.vhd

四位十进制频率计设计 包含测频控制器（TESTCTL）

LIBRARY IEEE;  
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY REG4B IS
    PORT (  LOAD : IN STD_LOGIC;
             DIN : IN STD_LOGIC_VECTOR(3 DOWNTO 0);
            DOUT : OUT STD_LOGIC_VECTOR(3 DOWNTO 0) );
END REG4B;
ARCHITECTURE behav OF REG4B IS
BEGIN
 PROCESS(LOAD, DIN)
  BEGIN
  IF LOAD'EVENT AND LOAD = '1' THEN  DOUT <= DIN; 

   END IF;
 END PROCESS;
END behav;